Toward Operational Satellite-Based Observations of Air-Sea Interaction Processes

Skillful forecasts on multiple time scales (days, weeks, months, years, decades) require coupled ocean-atmosphere models. Air-sea fluxes, which quantify the transfers of momentum, heat, and mass between the ocean and atmosphere, serve as boundary conditions in coupled models. Currently, the accuracy of the air-sea fluxes is limited for moderate and higher surface wind speeds when the waves start to break and create whitecaps, bubbles, and sea spray. Whitecaps, bubbles, and sea spray represent additional pathways for air-sea transfer, thereby enhancing all regular exchanges at the air-sea interface and in the upper ocean. However, these enhancements are poorly modeled due to insufficient data under higher wind conditions in the open ocean.

Using passive remote sensing observations of whitecap fraction W, air-sea processes and fluxes from breaking waves can be parameterized using global seasonal data. In addition, operational retrievals of W can provide daily air-sea interaction products useful for consistent, long-term monitoring of air-sea fluxes. In a recent project, we demonstrated the use of operational models for producing air-sea interaction data from Advanced Microwave Scanning Radiometer 2 (AMSR2) observations. We used the operational Navy Aerosol Analysis and Prediction System (NAAPS) to produce maps of sea spray aerosol optical depth in near-real time. We used the NRL Geolocated Information Processing System (GeoIPS) to demonstrate the processing cycle and visualization of daily whitecap fraction imagery and sea spray generation flux.

In our presentation, we will describe results of this demonstration project. These include: (a) Development of whitecap retrieval algorithm that uses brightness temperature and retrievals of geophysical variables from AMSR2 sensor; (b) Integration of whitecap fraction W and sea spray flux from daily AMSR2 data into GeoIPS framework to map them in north Atlantic study areas; (c) Expanding NAAPS capabilities with calculations of sea spray production flux using different W parameterizations based on both in situ and satellite W data. The results demonstrate the potential of the operational NAAPS and GeoIPS to improve existing and add new satellite-based air-sea interaction products.